• HEADINGS
  • METRIC CONVERSIONS
    • LENGTH
    • VOLUME
    • TORQUE
    • PRESSURE
  • CONVERSION FACTORS
• FIGURES
• TABLES
  • CONVERSION FORMULA
  • EQUIVALENCIES

GENERAL INFORMATION

English-Metric Conversion Chart

METRIC CONVERSIONS

Metric conversions are making life more difficult for the mechanic. In addition to increasing the number of tools required, metric-dimensioned nuts and bolts are used alongside English components in many new vehicles. The mechanic has to decide which tool to use, slowing down the job. The tool problem can be solved by trial and error, but some metric conversions aren't so simple.

Converting temperature, lengths or volumes requires a calculator and conversion charts, or else a very nimble mind. Conversion charts are only part of the answer though, because they don't help you "think" metric, or "visualize" what you are converting. The following examples are intended to help you "see" metric sizes:

LENGTH

Meters are the standard unit of length in the metric system. The smaller units are 10ths (decimeter), 100ths (centimeter), and 1000ths (millimeter) of a meter. These common examples might help you to visualize the metric units:

• A meter is slightly longer than a yard (about 40 inches).
• An aspirin tablet is about one centimeter across (.4 inches).
• A millimeter is about the thickness of a dime.

VOLUME

The metric weight system is based on the gram, with the most common unit being the kilogram (1000 grams). Our comparable units are ounces and pounds:

• A kilogram is about 2.2 pounds.
• A kilogram is about 2.2 pounds.

TORQUE

Torque is somewhat complicated. The term describes the amount of effort exerted to turn something. A chosen unit of weight or force is applied to a lever of standard length. The resulting leverage is called torque. In our standard system, we use the weight of one pound applied to a lever a foot long, resulting in the unit called a foot-pound. A smaller unit is the inch-pound (the lever is one inch long). Metric units include the meter kilogram (lever one meter long with a kilogram of weight applied) and the Newton-meter (lever one meter long with force of one Newton applied). Some conversions are:

• A meter kilogram is about 7.2 foot pounds.
• A foot pound is about 1.4 Newton-meters.
• A centimeter kilogram (cmkg) is equal to .9 inch pounds.

PRESSURE

Pressure is another complicated measurement. Pressure is described as a force or weight applied to a given area. Our common unit is pounds per square inch. Metric units can be expressed in several ways. One is the kilogram per square centimeter (kg/cm² ). Another unit of pressure is the Pascal (force of one Newton on an area of one square meter), which equals about 4 ounces on a square yard. Since this is a very small amount of pressure, we usually see the kiloPascal, or kPa (1000 Pascals). Another common automotive term for pressure is the bar (used by German manufacturers), which equals 10 Pascals. Thoroughly confused? Try the examples below:

• Atmospheric pressure at sea level is about 14.7 psi.
• Atmospheric pressure at sea level is about 1 bar.
• Atmospheric pressure at sea level is about 1 kg/cm² .
• One pound per square inch is about 7 kPa.

CONVERSION FACTORS

CONVERSION FORMULA

To Convert		To	Multiply By
LENGTH
Millimeters (mm)		Inches	.03937
Inches		Millimeters	25.4
Meters (M)		Inches	39.37
Meters (M)		Feet	3.28084
Feet		Meters	.3048
Kilometers (Km)		Miles	.62137
AREA
Square Centimeters (cm2 )		Square Inches	.155
Square Inches		Square Centimeters	6.45159
VOLUME
Cubic Centimeters		Cubic Inches	.06103
Cubic Inches		Cubic Centimeters	16.38703
Liters		Cubic Inches	61.025
Cubic Inches		Liters	.01639
Liters		Quarts	1.05672
Quarts		Liters	.94633
Liters		Pints	2.11344
Pints		Liters	.47317
Liters		Ounces	33.81497
Ounces		Liters	.02957
WEIGHT
Grams		Ounces	.03527
Ounces		Grams	28.34953
Kilograms		Pounds	2.20462
Pounds		Kilograms	.45359
WORK
Centimeter Kilograms		Inch Pounds	.8676
Pounds/Sq. Inch		Kilograms/Sq. Centimeter	.07031
Bar		Pounds/Sq. Inch	14.504
Pounds/Sq. Inch		Bar	.06895
Atmosphere		Pounds/Sq. Inch	14.696
Pounds/Sq. Inch		Atmosphere	.06805
TEMPERATURE
Centigrade Degrees		Fahrenheit Degrees	(C°x9 /5 )+32
Fahrenheit Degrees		Centigrade Degrees	(F°-32)x5 /9

EQUIVALENCIES

Inches	Decimals	mm
1/64	.016	.397
1/32	.031	.794
3/64	.047	1.191
1/16	.063	1.588
5/64	.078	1.984
3/32	.094	2.381
7/64	.109	2.778
1/8	.125	3.175
9/64	.141	3.572
5/32	.156	3.969
11/64	.172	4.366
3/16	.188	4.763
13/64	.203	5.159
7/32	.219	5.556
15/64	.234	5.953
1/4	.250	6.350
17/64	.266	6.747
9/32	.281	7.144
19/64	.297	7.541
5/16	.313	7.938
21/64	.328	8.334
11/32	.344	8.731
23/64	.359	9.128
3/8	.375	9.525
25/64	.391	9.992
13/32	.406	10.319
27/64	.422	10.716
7/16	.438	11.113
29/64	.453	11.509
15/32	.469	11.906
31/64	.484	12.303
1/2	.500	12.700
33/64	.516	13.097
17/32	.531	13.494
35/64	.547	13.891
9/16	.563	14.288
37/64	.578	14.684
19/32	.594	15.081
39/64	.609	15.478
5/8	.625	15.875
41/64	.641	16.272
21/32	.656	16.669
43/64	.672	17.066
11/16	.687	17.463
45/64	.703	17.859
23/32	.719	18.256
47/64	.734	18.653
3/4	.750	19.050
49/64	.766	19.447
25/32	.781	19.844
51/64	.797	20.241
13/16	.813	20.638
53/64	.828	21.034
27/32	.844	21.431
55/64	.859	21.828
7/8	.875	22.225
57/64	.891	22.622
29/32	.906	23.019
59/64	.922	23.416
15/16	.938	23.813
61/64	.953	24.209
31/32	.969	24.606
63/64	.984	25.003
1	1.000	25.400

Release January 2015